Lossless Intermediates

~8 min · lossless, intermediate, ffv1, ut

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When intermediate matters

If you're doing multi-step processing (extract → grade → composite → re-encode), each lossy step compounds artifacts. Use a lossless intermediate format between steps: every byte preserved, scrubbing fast.

Three options

ffv1 — open, lossless, slow encode but small (compressed lossless). Good for archival.
utvideo — open, lossless, fast. Slightly bigger files, much faster encode.
ProRes — Apple's mostly-lossless intermediate. Not strictly lossless but visually transparent. See Track 3 lesson 4.

Code

Lossless intermediate recipes·bash

# ffv1 in MKV — small, slow, lossless
ffmpeg -i in.mp4 -c:v ffv1 -level 3 -coder 1 -context 1 -g 1 \
  -c:a flac \
  intermediate.mkv

# Ut Video — larger but fast (good for editor scratch)
ffmpeg -i in.mp4 -c:v utvideo -pred median \
  -c:a flac \
  intermediate.mkv

# ProRes 4444 (visually lossless, broadly compatible with editors)
ffmpeg -i in.mp4 -c:v prores_ks -profile:v 4 \
  -pix_fmt yuv444p10le -vendor apl0 \
  -c:a pcm_s16le \
  intermediate.mov

External links

Exercise

Take an H.264 MP4. Encode it to ffv1, utvideo, and ProRes 4444. Note file sizes. Decode each back and re-encode to H.264 — does the final output differ from going H.264 → H.264 directly? (Use VMAF or just visually compare full-screen.) Which intermediate would you actually pick?